EU 10/2011 EG 1935/2004CERTIFIED

Dust Dust explosion constant Examples

ST 0 Kst = 0 Cement, chalk, sand, ash, aerosol, salts

ST 1 0 < Kst ≤200 Flour, malt dust, many corn starches, sugar dust, many wood types, sulphur, coal dust, PVC dust, carbon black

ST 2 201 < Kst ≤300 A single corn starch type, beech wood dust, epoxy resin, methyl cellulose, paraformaldehyde, some pigments, some powder aromas and vitamins

ST 3 Kst > 301 Aluminium, magnesium, red phosphorus, Anthraquinone

EU 10/2011 EG 1935/2004CERTIFIED

Product:Degree of risk Required category for the device

Gas/Vapour Dust

Zone 0 Zone 20 Where there is a continuous, long-lasting or frequently occurring explosive environment Category 1

Zone 1 Zone 21 Where an explosive environment is likely to occur Category 2

Zone 2 Zone 22 Where an explosive environment is unlikely to occur, and if so, only rarely and for a short time Category 3

Symbol Meaning

B Management of ignition sources

BZ Fire number

c Safe construction

d Explosion hazard

dp/dtmax Maximum rate of pressure rise

e Increased safety

Emin Minimal ignition energy

fr Restricted breathing enclosure

i Intrinsic safety

k Protection by immersion

Kg Gas explosion constant

Kst Dust explosion constant

LEL Below explosion limits

m Embedded material

mD Cast

MIE Minimal ignition energy

MOT Minimum cloud ignition temperature

n Non-sparking material

o Immersion in oil

p Overpressure protection

Pmax Maximum explosion pressure

q Powdered fi lling

St 0 t/m 3 Dust classifi cation

T1 t/m 6 Temperature class

tD Protection by enclosure

TglimMinimum ignition temperature of the dust layer

TminMinimum ignition temperature of the cl-oud

UEL Above explosion limit

Ignition source

1. Hot surfaces

2. Falames and hot gases (including hot particles)

3. Mechanically generated sparks

4. Electrical apparatus

5. Stray electrical currents, cathodic corrosion protection

6. Static electricity

7. Lightning

8. Radio frequency (RF) electromagnetic wavees from 104 Hz to 3 x 1012 Hz

9. Electromagnetic waves from 3 x 1011 Hz to 3 x 1015 Hz

10. Ionising radiation

11. Ultrasonics

12. Adiabatic compression and shock waves

13. Chemical reactions, including self-ignition of dusts

EU 10/2011 EG 1935/2004CERTIFIED